The present invention relates to the interface between a circuit breaker operating mechanism and a multipole circuit breaker, and, more particularly, to the precision location of a trip actuator unit mounted on the cover unit and a circuit breaker operating mechanism to trip a multipole circuit breaker.
In a circuit breaker of a phase cassette concept, the functional relationship between the operating mechanism and the trip actuator unit is such that when the trip actuator unit indicates a trip signal, the actuator must interface with the mechanism at the trip latch to open the breaker. Tolerances in the system hinder this functional relationship. A precision relation must necessarily be established between the circuit breaker operating mechanism and the trip actuator unit.
In U.S. Pat. No. 5,281,776 entitled xe2x80x9cMultipole Circuit Breaker With Single-Pole Unitsxe2x80x9d, single-pole units of a general box-like parallelepipedic shape are arranged side-by-side and are linked by alignment rods extending perpendicularly through the opposing side faces of each box. Since the internal components of each single-pole unit are framed laterally with a small clearance by the opposing side faces and are free to move slightly in other directions to compensate for irregularities in manufacturing or positioning, a certain amount of tolerance buildup results. Excessive tolerance buildup may cause the inadequate performance of the circuit breaker.
In U.S. Pat. No. 5,581,219 entitled xe2x80x9cCircuit Breakerxe2x80x9d, the trip actuator unit is in the form of a cassette detachably mounted on a molded base, and the molded base is detachably mounted to a cover of a circuit breaker casing. The cover rests on the casing of the unit, and the trip actuator unit and other accessories are properly located on the breaker by being mounted in recesses formed in the cover.
Because a precision spatial relationship is required between the trip actuator unit and the breaker operating mechanism for the proper functioning of the circuit breaker, tolerances in the system must be minimized. In order to minimize these tolerances, clearances between parts are eliminated by bringing parts into physical contact with each other and by dimensioning the circuit breaker such that critical components have a direct spatial relationship with other critical components.
The above discussed and other drawbacks and deficiencies are overcome or alleviated by a precision location system for a circuit breaker utilizing a phase cassette concept. The precision location system is between an actuator accessory and an operating mechanism in the circuit breaker having a cover plate configured to receive the actuator accessory. The cover plate is further configured to receive the operating mechanism and is configured to align the actuator accessory with said operating mechanism when the actuator accessory and operating mechanism are received in said cover plate.
In an exemplary embodiment, the cover plate has a first protrusion depending therefrom, which contains an alignment groove configured to engage an alignment rod extending through a plurality of single-pole breaking units to align the same. The alignment groove may or may not conform to the outer shape of the alignment rod. A second protrusion containing an alignment groove may depend from the cover plate to engage the same alignment rod at a different point, thereby providing additional side-to-side securement of the cover plate on the alignment rod. In an alternate embodiment, the alignment grooves may snappingly engage the alignment rods. A location tab disposed on the actuator provides a means for precisely mounting the actuator on the cover plate, thereby precisely locating the trip actuator unit on the circuit breaker operating mechanism.
Because the operating mechanism and the actuator accessory are mounted on different components within the phase cassette system, a location system is preferably utilized to precisely define the relationships between all of the components involved. The location system thus allows for a closely toleranced relationship between the cassette and the trip actuator unit by utilizing at least one alignment rod extending laterally through breaking units within the phase cassette assembly.